1. Field of the Invention
This invention relates to an aqueous solution of a strong alkali and a nonionic surface active agent, and, more particularly to an aqueous solution composition of a strong alkali and a nonionic surface active agent having an HLB value of 3-18 at high concentrations and stably.
2. Description of the Background
Strong alkalis, for example, sodium hydroxide, potassium hydroxide, sodium orthosilicate, and sodium metasilicate, are used for such applications as neutralization of an acid, saponification reactions of oils and fats (triglycerides), and the like. Also, these alkalis are useful in various industrial applications because of their good electric conductivity. Nonionic surface active agents, on the other hand, are very useful as effective ingredients or detergency improvers of various kinds of detergent compositions owing to their emulsifying, dispersing, and foaming capabilities, as well as to their permeability. They are also effective as wettability promoting agents of glass, fiber, metal, and earthenware surfaces. Because of these characteristics, nonionic surface active agents are widely used in industries in general and for various toiletry products.
Therefore, a combination of a strong alkali and a nonionic surface active agent is expected to produce a composition which is strongly alkaline and at the same time exhibits a high degree of functionality in terms of emulsifying, dispersing, and foaming capabilities, and of permeability.
Preparing an aqueous solution containing both a strong alkali and a nonionic surface active agent at high concentrations, however, has been extremely difficult. Because of this, when a strong alkali and a nonionic surface active agent have to be used together, it has been necessary to supply a solid material in a powdery or flaky form containing a strong alkali and a nonionic surface active agent, or to first supply a strong alkali and a nonionic surface active agent separately as liquids, and then blend the two liquids together when used.
Handling a strong alkali in a powdery or flaky form, however, involves difficulties in actual operation. For example, there is the risk of splashing or generating a mist of the strong alkali in the air. The splashing or misting causes problems in view of human safety and sanitation. For instance, they produce considerable irritation when coming into contact with the skin. Blending liquids of a strong alkali and a nonionic surface active agent is a cumbersome task in itself. In addition, adjusting the concentration of each component requires complicated control.
Due to this situation, the development of an aqueous solution containing both a strong alkali and a nonionic surface active agent at high concentrations has been strongly desired.
A certain action due to a salting-out effect owing to loss of hydration water necessary for dissolving a nonionic surface active agent, which results from dissociated ions of an inorganic strong alkali, has generally been considered to be the cause of the difficulty in preparing this type of strong alkali-nonionic surface active agent aqueous solution.
The present inventors have undertaken extensive studies to eliminate the occurrence of this kind of action, and found that the use of a specific type of carboxylic acid or the salts thereof, as a solubilizing agent, is effective in achieving this target. Such a finding has led to the completion of this invention.